China3D printingNet, April 22, researchers and engineers from the Massachusetts Institute of Technology (MIT) are using3D printingTechnology, using conductive polymer liquid materials to develop soft and flexible brain electrodes.
MIT engineers are working on the conductive polymer3D printingFor research, they are researching and developing soft nerve implants that conform to the contours of the brain and monitor activities for a longer period of time without aggravating the condition of surrounding tissues.
Brain implants, usually made of metal, can cause inflammation and accumulation of scar tissue. 3D printingThe use of flexible polymer electronic devices can potentially provide a softer, safer, and faster alternative to existing metal-based electrodes designed to monitor brain activity. Therefore, this research may also be useful for developing brain implants that stimulate nerve areas to relieve symptoms of epilepsy, Parkinson’s disease, and severe depression.
Flexible nerve electrode with3D printingThe soft electron active polymer. The picture comes from the Massachusetts Institute of Technology.
3D printingConductive polymers
In a recently published study, an MIT research team led by Professor Zhao Xuanhe of Mechanical Engineering and Civil and Environmental Engineering outlined a3D printingNerve probes and other electronic devices that are as soft and flexible as rubber. The research focused on conductive polymers, which are a class of polymers with inherent conductivity. They are used commercially as antistatic coatings because they can effectively remove any static charge that accumulates on electronic equipment and other surfaces that are prone to static electricity.
“These polymer solutions are easy to spray on electronic devices such as touch screens,” said Hyunwoo Yuk, a graduate student in Zhao’s group at MIT. “But the liquid form is mainly used for homogeneous coatings, and it is difficult to apply them to any two-dimensional. High-resolution patterns. In 3D mode, this is impossible.”
In this article, the researchers introduced a 3D printable conductive polymer ink solution based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS). Generally, it is a liquid conductive polymer solution containing nanofibers that provide the material with conductive properties.The MIT research team turned this substance into a thickening material similar to “sticky toothpaste” to make it3D printing, While still retaining the inherent conductivity of the material.
Make PEDOT: PSS solution compatible with3D printingCompatible processes include freeze-drying the material, removing the liquid and leaving a dry nanofiber matrix. These nanofibers are then mixed with their previously developed solutions of water and organic solvents to form hydrogels embedded in the nanofibers.By experimenting with different hydrogel forms, the researchers found that the weight percentage of nanofibers is between 5% and 8%, which can produce toothpaste-like materials that are both conductive and suitable for feeding3D printingmachine.
“Initially, just like soapy water, we concentrated the nanofibers to make it viscous like toothpaste, so we can squeeze it out as a dense printable liquid.”
By feeding new, thicker conductive polymer into3D printingIn the machine, the researchers were able to create a stable conductive pattern. Therefore, the team used the PEDOT:PSS solution to create several conductive polymer devices, including soft rubber-like electrodes, and implanted them into the brains of mice as a proof of concept.
Yuk added: “We hope that by demonstrating this concept, people can use this technology to quickly manufacture different devices.
“They can change the design, run the printed code and generate a new design within 30 minutes. This can completely simplify the development of a neural interface made entirely of soft materials.”
The team also printed a soft multi-electrode array. The picture comes from the Massachusetts Institute of Technology.
test3D printingelectrode
The small electrode consists of a layer of soft transparent polymer, on which the MIT team 3D converges the PEDOT:PSS material in thin parallel lines. The line converges on a tip with a width of about 10 microns. Its size ensures that the electrode has the ability to pick up electrical signals from a single neuron (that is, a cell that uses electrical impulses to transmit information in the brain). Through testing, the researchers found that the implanted electrode can indeed detect the electrical signal from a single neuron in the rat’s brain because it moves freely in a controlled environment.
Standard nerve implants use metal electrodes to stimulate and monitor parts and structures of the nervous system. This can give scientists a clearer understanding of brain activity and help tailor therapies and long-term brain implants for various neurological diseases (such as Parkinson’s disease).
3D printingThe SEM image of the conductive polymer grid is 200 µm” alt=”3D printingThe SEM image of the conductive polymer grid is 200 µm” width=”620″ height=”345″ />
3D printingThe SEM image of the conductive polymer grid is 200 µm. The picture comes from “Nature Communications”.
In addition to the potential for damage to brain tissue under vibration, in principle, metal electrodes are less sensitive to electrical signals in the brain than hydrogel-based electrodes. This is because metal electrodes conduct electricity in the form of electrons, while neurons in the brain produce electrical signals in the form of ions-which means that ionic currents need to be converted before they can be recorded by the metal electrodes. This may cause some parts of the signal to be lost in translation.According to China3D printingNet understands, in contrast,3D printingThe soft electrode is made of conductive nanofibers embedded in a hydrogel, which is a water-based material through which ions can pass freely.The beauty of conductive polymer hydrogel lies in its soft mechanical properties. It is made of ion-conductive hydrogel and nanofiber porous sponge, and ions can flow in and out. Since the entire volume of the electrode is active, the sensitivity is improved.
In the field of nerve implants3D printing
Although unique in the use of conductive polymers, the MIT research team is not the first to use3D printingPeople who create nerve implants.As early as 2019, researchers at Carnegie Mellon University published a study that used 3D nanoparticle printing technology to create high-density neural probes to record neurological data. The project received a $1.95 million grant from the National Institutes of Health (NIH).
Two months later, Qrons, a New York-based biotechnology startup, announced an intellectual property (IP) license agreement with Dartmouth College in New Hampshire to develop 3D printable implants to treat penetrating or traumatic brain injuries (TBI).
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